This commit makes sure that if a `javax.cache.CacheManager` is required,
an auto-configured `HazelcastInstance` is fully resolved first. This
prevents the case where the JCache bootstrap actually starts an instance
early, followed by a second (potentially unwanted) instance created by the
regular auto-configuration.

Since the JCache implementation works with an `HazelcastInstance` behind
the scenes, if there is one `HazelcastInstance` configured and it has a
name, then we configure the `CacheProvider` to use that. Future Hazelcast
version will allow to pass the instance directly (i.e. not requiring an
actual name).

Closes gh-8484